1. Field of the Invention
Embodiments of the present invention relate to integrated circuit design, and, more particularly, to input processing of differential pair inputs.
2. Description of the Related Art
The current state of integrated circuit technology is such that circuit designs are able to process data at rates which can challenge the ability to provide sufficient input data to keep the circuit designs at a high operating efficiency. Thus, the frequency of data transfer between circuit designs continues to increase, resulting in increase signal frequencies. This increase in signal frequency applies to both interchip as well as intrachip communication. For example, an address generation circuit in a processor may be in need of obtaining a cached address from an on-chip cache. With the operating frequency of the address generating circuit rapidly increasing with successive generations of integrated circuit technology, providing timely data from the cache to the address generating circuit may be a challenge. Thus, the communication link between the cache and the address generation unit may attempt to use a high-speed communication link.
Differential signaling, as opposed to single ended signaling, provides advantages that may result in an increased maximum operating frequency. In differential signaling, typically two component signals (sometimes referred to as a differential pair) are used to transmit data instead of one signal, as with single ended signaling. The data value on a differential pair is represented as the difference between the voltage on the two signal components. An example of a common differential signaling protocol is low-voltage differential signaling (LVDS). LVDS uses high-speed analog circuit techniques to provide data transfers on interconnects and is a generic interface standard for high-speed data transmission.
Differential signaling provides a number of benefits. Many noise sources are not local to a differential pair. Thus, these noise sources will affect both signals of the differential pair relatively evenly. By affecting both signals of the differential pair relatively evenly, the difference between the two signals will remain relatively constant. Thus, differential signaling provides improved noise immunity compared to a single wire solution. Other advantages are associated with differential signaling as well. When low voltage differential signaling is utilized, the low voltage differential allows for higher switching speeds when compared to large voltage differential signaling and single ended signaling. Thus, differential signaling provides advantages over traditional single ended signaling and is therefore utilized to provide a high-speed communication link between a source and a destination function block.